1). Field of the Invention
This invention relates generally to a semiconductor processing system and, more specifically, to a semiconductor processing system having a semiconductor processing chamber with an infrared light transmitting wall.
2). Discussion of Related Art
FIG. 1 of the accompanying drawings illustrates a conventional semiconductor processing system 10 which is used for subatmospheric pressure processing of a wafer 12. The semiconductor processing system 10 includes a semiconductor processing chamber 14, wafer handling apparatus 16 within the semiconductor processing chamber 14, and a lamp head 18 on the semiconductor processing chamber 14.
The semiconductor processing chamber 14 includes a lower main body 20 and an upper wall 22 comprising a lower quartz window 24, an upper quartz window 26, and a strengthening component 28 which is sandwiched between the lower and upper windows 24 and 26.
The strengthening component 28 is made of stainless steel and comprises two spaced plates 30 and a surrounding ring 32 which jointly define an enclosed volume. A port 34 extends through the ring 32 and may be connected to a pump which is operable to reduce the pressure within the enclosed volume defined by the plates 30 and the ring 32. A plurality of tubes 36 are welded into through holes and in plates 30.
The lower window 24 is made of quartz and protects the internal dimensions of the semiconductor processing chamber 14 against contamination from the material of the strengthening component 28.
A number of infrared lamps 38 are located in the lamp head 18. During processing, infrared radiation from lamps 38 radiate through the upper window 26, tubes 36 and the lower window 24 onto the wafer 12. In this manner, the wafer 12 is heated to a required processing temperature.
During processing, the pressure within the semiconductor processing chamber 14 is maintained at a subatmospheric pressure. The reduced pressure within the semiconductor processing chamber 14 results in a negative pressure on the lower surface of the lower window 24. The pressure within the enclosed volume defined by the plates 30 and the ring 32 is reduced to a pressure which is lower than the pressure within the semiconductor processing chamber 14 in order to prevent collapse of the lower window 24 and the lower of the plates 30 into the semiconductor processing chamber 14.
A processing gas is then introduced into the semiconductor processing chamber 14 for purposes of processing the wafer 12. This gas usually forms a contaminant layer on an inner surface of the semiconductor processing chamber 14, including on the lower window 24, and on the wafer handling apparatus 16. The contaminant layer eventually forms to a thickness on the lower window 24 which prevents infrared light from suitably reaching the wafer 12.